Organic transistors are preferable for applications such as electronic paper and flexible displays and have attracted attention in recent years, because they are inexpensive and have properties such as flexibility and bendability.
Organic transistors include layers composed of organic materials and having charge (meaning hole and electron; hereinafter the same) transport properties, and organic semiconductor materials are mainly used as such organic materials. Polymer compounds which can form layers (i.e., organic semiconductor layers, also generally called active layers) in the state of solutions in solvents by coating have been studied, for example, polymer compounds having only the thiophene backbone have been proposed, as such organic semiconductor materials (Non Patent Literature 1).